Textured Bi2Sr2CaCu2O8+delta high temperature superconductors: mechanical properties

The mechanical properties of Bi2Sr2CaCu2O8+delta superconductor fibres proc essed by laser-induced directional solidification at different growth rates were studied. Tensile and diametral compression (Brazilian test) tests wer e performed to analyse the longitudinal and transversal strength. The elast ic modulus was determined using the flexural vibration resonance method. Fl exure tests were also carried out to compare with the literature data. In a ddition, polished sections of the as-received fibres and the fracture surfa ces of the broken samples were analysed in the scanning electron microscope . The fibres were highly anisotropic and the transverse fibre strength was very low due to the early failure by cleavage of the grains perpendicularly to the c axis. The degree of anisotropy and the longitudinal strength incr eased as the fibre growth rate decreased while the transverse strength foll owed the opposite trend. This behaviour was due to changes in the porosity and the alignment of the crytals along the fibre axis.